Treatment of casein



Patented a. "12, 1937 PATENT OFFICE.

2,095,887. TREATMENT or CASEIN William Howard Nicol, Cuyahoga Falls,Ohio,-

signo'r to Wingfoot Corporation, Wilmington, Del., a corporation ofDelaware No Drawing.

Application July 5, 1935,

Serial No. 30,020

1 Claim. ('01. 134-23.!

. This invention relates to the treatment of casein and moreparticularly to the preparation oi. casein for use in cements oradhesives.

A true aqueous solution of casein is desired.

for compounding with other ingredients in the 0 ward alkalies.

preparation of certain adhesives, etc. It has been found that commercialgrades of casein which are dried out to different degrees and aged fordifferent lengths of time react differently to- Particular care musttherefore be taken to obtain from different batches of casein a solutionwhich will have uniform physical and/or chemical pro rties. For example,in the preparation of adhesives, in which an alkaline 1 medium isemployed to make the casein soluble in water, care'must be taken toproduce a homo'' geneous aqueous solution. In using ammonia, forexample, if the casein is not in a finely divided condition it will notentirely react with the am- 20 monia to give water-soluble ammoniumcaseinate. With large particle size casein the am-.

monia or other water solubilizing compound may form a lumpy caseinatenot entirely in solution. According to this invention casein is ballmilled with ammonia or other alkaline solubilizing compound toproducethe caseinate'solution which is then mixed with latex or otheringredients to form an adhesive. The dried casein, which may be composedof pieces dried to adifferent extent 0 and aged for a difierent lengthof time, is subdivided to a size suitable for ball milling. For thispurpose the casein is preferably reduced to 40. to 100 mesh. Thisisball-milled with water for an hour. At the end of this time the caseinhas softened. Sometimes it swells in the water and at other times themixture assumes a milklike appearance. Then alkali is added, such asammoni and the ball milling is continued for refera 1y another hour.Preferably only part 0 of the total water is added to the mill duringthe preliminary treatment, 1. e., before the addition of the alkali, andthe balance of the water. isadded at the same time as' the alkali. Thistreatment gives a uniform caselnate regardless of the 5 original stateof the casein supplied to the mill. The dissolved caseinate thusobtained may be mixed with latex in any suitable proportions to make agood adhesive.

The grinding of the casein with water prior too the addition of alkalisoftens the casein. In this state it is readily acted on by thesolubilizing agent. to grind the casein for too long a period in thispreliminary stage of the treatment.

. u The following example illustrates the process:

It will ordinarily be found desirable not 31.9 pounds of casein are ballmilled with 318.8 pounds water for one hour, after which 133.9 poundswater and 19.1 pounds of concentrated ammonium hydroxide (28%) areadded. This mixture is then ball milled for another hour during whichtime the casein reacts with the ammonia forming the water solubleammonium caseinate. The solution is preferably effected at roomtemperature, i. e. without heating tn" cool- ,ing. A desirable adhesiveis made by mixing the resulting solution with about 134 poundsofcommercial concentrated latex of 60% rubber content. Neither the caseinafter wetting or after being brought into solution, nor the adhesiveformed from the latex should be stored forany considerable length oftime as the casein tends to spoil. -Age resisters, and preservativessuch ashydroquinone, sodium chloro phenyl phenate, and sodiumorthophenyl phenate may be used to prolong the time .before spoilagecommences.

According to another procedure about 28.2 pounds of pulverizedlcasein isball milled or one hour with 10.2 pounds of water. To this about 14.1

.pounds of concentrated ammonia (containing 26 to 28% of NHa) is addedand the ball .milling continued for another half hour. If this is to beused with latex it may be diluted with morewater, for example enough toreduce the concentration of original casein present to 6%%.

Instead of ammonia, other alkalies such as diethanol amine, ethylenediamine, diethylene triamine, propylene diamine, diethylene tetramine,sodium carbonate, sodium hydroxide, borax and potassium hydroxide andthe like may be employed to solubilize the casein for various differentpurposes. For the preparation of a caseinlatex adhesive to be used tocement rubber to rayon in the manufacture of automobile tires, ammoniawill, in general be found most satisfactory.

Various commercial forms of casein may be satisfactorily treated in thisway, such as muriatic acid casein, coagulated caseins (low and highviscosities) rennet casein, lactic acid casein, and sulfuric-acidcoagulated casein (medium and high, viscosities) Where the caseinemployed varies little in properties from batch to batch the time 'ofball milling prior to adding the alkali may be materially reduced andthe timeof ball milling after adding the alkali may be reduced. Wherethe source of casein'is not uniform and the casein supplied to differentbatches varies to a considerable extent it will be found that by ballmilling with water for about an hour and then adding alkali and againball milling for about an hour, a product which is relatively uniformfrom one batch to the next will be obtained.

This is in part a continuation of co-pending application Serial No.655,248 filed February 4, 1933.

I claim:

The method of preparing from dried pieces of 1 casein, caseinatesolutions suitable for use in

